It is only in recent years that scientists are starting to
recognize the influence of atmospheric and oceanic cycles in influencing
climate.

A 2008 study – “Oceanic Influences on Recent Continental Warming”,
by Compo, G.P., and P.D. Sardeshmukh, (Climate Diagnostics Center, Cooperative
Institute for Research in Environmental Sciences, University of Colorado, and
Physical Sciences Division, Earth System Research Laboratory, National
Oceanic and Atmospheric Administration), Climate Dynamics, 2008)

[http://www.cdc.noaa.gov/people/gilbert.p.compo/CompoSardeshmukh2007a.pdf]
states: “Evidence is
presented that the recent worldwide land warming has occurred largely in
response to a worldwide warming of the oceans rather than as a direct
response to increasing greenhouse gases (GHGs) over land. Atmospheric model
simulations of the last half-century with prescribed observed ocean
temperature changes, but without prescribed GHG changes, account for most of
the land warming. … Several recent studies suggest that the observed SST
variability may be misrepresented in the coupled models used in preparing the
IPCC's Fourth Assessment Report, with substantial errors on interannual and
decadal scales. There is a hint of an underestimation of simulated decadal
SST variability even in the published IPCC Report.”

This document describes the combination of the Pacific
Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO).

In a CRU email between Edward Cook and Michael Mann in May
2001, Cook stated: “most
researchers in global change research would agree that the emergence of a
clear greenhouse forcing signal has really only occurred since after 1970. I am not debating this point,
although I do think that there still exists a significant uncertainty as
to the relative contributions of natural and greenhouse forcing to warming
during the past 20-30 years at least.” [http://www.eastangliaemails.com/emails.php?eid=228&filename=988831541.txt]

The figure below right superimposes the CRU temperature
anomalies on the IPCC graph of model outputs. (IPCC 2007 AR4 Figure SPM-4 [http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf])
In this figure, the blue shaded bands show the result climate model simulations
using only natural forcings. Red shaded bands show the result model
simulations including anthropogenic CO2.

This clearly shows that prior to about 1973, the global
warming is fully explained by climate models using only natural forcings
(i.e. no human CO2). The models need input of CO2 only after about the
mid-1970s – prior to 1970 all warming was natural, according to the IPCC.

The following figure temporally aligns the
graphs of PDO, AMO and global temperature. Periods of synchronization of PDO
+ AMO are indicated by the vertical shaded bars.

The following figure shows the 5-year means of PDO, AMO
and PDO + AMO.

The next figure shows the US temperature anomalies as calculated
by NASA’s James Hansen (2001). The periods when the temperature anomalies are
positive correspond almost exactly to when the PDO+AMO changes between warm
and cool phases.

The following figure compares the PDO+AMO with the US average annual temperatures. D’Aleo calculated an r-squared of 0.85 between the two – an
extremely good correlation.

The next figure compares the same temperature data with
atmospheric CO2. D’Aleo calculated an r-squared of 0.44 between the two – a
fair correlation, but poor in comparison to the PDO+AMO correlation. Although
correlation does not prove causation, lower correlation is evidence of lower
probability of causation.